There already exist treatment installations comprising one or several furnaces or a plurality of vats and means for successively transferring a batch from a loading point into the furnace then into the vat and then for extracting this batch from the vat and bringing it to an exit point. We cite in particular the European patent application no. 0 296 102, published on 21 Dec. 1988.
The Swiss patent CH-478 918 also describes an installation of this type. In this latter, the bell is suspended inside the furnace by suspension means capable of making it turn about its axis when the lift is in the upper position, so that the batch can be placed on projecting supports which are integral with the inner wall of the bell.
This prior art installation allows the batch to be transferred from the lift to the furnace and then from the latter to the hardening vat, but it is a tricky operation to keep the batch secured to the bell and moreover, when the furnace is displaced from the loading position to the position for transfer into the vat, the bottom of the furnace is open and therefore the batch is subject to the risk of oxydation. Another disadvantage of this prior art installation is that the means for suspending the bell prevent a gas circulation turbine from being placed at the most favourable location, i.e. at the top of the furnace in the axis of the bell.